Parsley-Shallot Butter From 'Prune'

Ingredients (5)

• 2 garlic cloves, peeled
• 3/4 cup peeled and coarsely chopped shallots
• 2 cups picked-clean parsley leaves
• 1 1/2 teaspoons salt
• 1 pound unsalted butter cut into 1-inch cubes, at coolish room temperature